Traditional printing methods require the formation of regions of colour on a substrate by the direct application of pigmented material to a substrate. This may be achieved using various standard methods (such as inkjet printing), thermal transfer and photographic techniques. Standard printing requires ink consumables and thermal transfer has consumable ribbons. Photographic techniques require liquid developers and fixing agents.
As an alternative to such methods, inkless printing methods were developed, using a dry process requiring no consumables at the time of fixing an image. A known inkless printing method involves providing a substrate comprising or having added to it photosensitive materials such as diacetylenes. These materials are susceptible to change colour when exposed to a suitable energy source such as a laser. In order to print a desired image, a laser beam is steered relative to the substrate so as to selectively irradiate various areas of the substrate. The subsequent colour change of the irradiated areas forms the image.
The above inkless printing methods and systems for implementing them have disadvantages. In particular, they are relatively limited in the colour change they can achieve and/or the level of control over the said colour change. This limits the effectiveness of such techniques and consequently limits commercial interest in their uptake.
It is therefore an object of the present invention to provide a solution that at least partially overcomes or alleviates the above problems.